The present invention relates in the first place to a method for the manufacture of a matrix using an original.
More particularly the present invention relates to a method for the manufacture of a matrix which will be able at least to display a surface section with a negative microstructure, intended for replication as a positive microstructure on an object, such as a plastic component, produced in a plastic moulding machine.
Matrices of this type are suitable for inclusion as a mould insert in a mould cavity in a unit producing plastic components, in order to assign said plastic components a positive microstructure in a corresponding surface section.
Concepts like negative or positive microstructure are used in this application solely for the purpose of being able to elucidate the altered shape of the microstructure in the matrix or in the mould-cavity insert and the replicated microstructure in the plastic component.
The invention also relates to a matrix, suitably manufactured in accordance with the method.
The manufacture of matrices in accordance with the method for the present invention is based on using an original with a surface section displaying a sharp positive microstructure in order to apply on this original at least one layer of material and/or a mixture of materials producing a matrix, this material having been selected to withstand the forces exerted on a mould-cavity insert in a machine for moulding plastic components.
When the matrix or mould-cavity insert has been completely built up, measures are taken to remove the matrix from said original or remove the material in the original, so that the microstructure-related surface section of the matrix, with a sharp negative microstructure, will appear.
The present invention relates more particularly to use in applications where the microstructure is chosen with a groove width or the like of less than 500 xcexcm, for instance in the range of 50-0.1 xcexcm, but may naturally be used for greater groove widths.
Although the invention indicates the possibility of forming a matrix, for inclusion in a unit producing plastic components such as a mould-cavity insert, on an original such as a silicon disc, the invention also enables a second matrix with reverse microstructure to be formed from such a matrix or the like.
Regarding the properties associated with the present invention it can be mentioned that patent publication EP-A1-0 400 947 shows a method to be already known for manufacturing a substantially independent diamond or diamond-like film (16) with a desired profile, the method comprising:
the application of a thin carbide layer (14) on a fixed substrate (10) having a surface (12) with a form corresponding to the desired profile,
the application of a film (16) consisting of crystalline diamond or a diamond-like film, on the carbide layer (14), and removal of the substrate (10).
Patent publication EP-A10 417 924 shows a method for manufacturing moulded diamond articles, the method comprising:
the formation of a reactive gas or chemical vapour, said gas comprising active carbon and means for forming a diamond deposit on a predetermined substrate,
the use of a non-flat model of predetermined shape, the surface of the model being such that a layer of diamond can be built up from said vapour,
where the non-flat model is also assigned the ability to release a diamond layer formed by a chemical vapour phase being deposited thereon,
the formation of a layer of synthetic diamond against the non-flat model by allowing the surface of the non-flat model to be brought into contact with the vapour under such conditions that the diamond buildup produces a synthetic diamond article, the shape of which conforms to the shape of the non-flat model, and
removing the synthetic diamond article from said non-flat model.
Also pertaining to prior art is an article entitled xe2x80x9cCVD Replication for Optics Applicationsxe2x80x9d by Jitendra S. Goela and Raymond L. Taylor, published in SPIE, Vol. 1047, xe2x80x9cMirrors and Windows for High Power/High Energy Laser Systemsxe2x80x9d (1989), describing a deposition process using a chemical vapour in order to replicate shapes, patterns and highly reflective surfaces in optical material (ZnS, ZnSe) and mirror material (Si, SiC) transferable in infrared rays, for several applications.
A method is also known through patent publication EP-A1-0 442 303 for producing three-dimensional workpieces or components made of diamond, comprising:
a) placing a model heated to a CVD diamond-forming temperature (500 to 1100xc2x0 C.) in a chamber, the model constituting a negative of the workpiece,
b) applying or supplying a gas mixture of hydrocarbon/hydrogen to said chamber at a pressure of 0.013 to 1334 mbar (0.01 to 1000 torr),
c) creating at least a partial degradation or decomposition of said gas mixture in, said chamber to form a CVD diamond layer on more than one surface of said model, and
d) removing said model from said CVD diamond layer to produce said diamond workpiece, which will thus display the surface characteristics of the surface of the model on which it was formed.
More particularly, FIGS. 5A, 5B and 5C show a step-shaped or groove-shaped pattern manufactured from molybdenum, in which identical parallel grooves form a check pattern with 5 mm spacing after machining.
Groove 32 has a width of 0.03 inch (0.76 mm) and a depth of 0.013 inch (0.33 mm), with 5 mm between the centre lines of the grooves. The thickness of the plate is chosen as 3.81 mm.
Parts of the workpiece 34 are soldered to a carbide substrate in order to produce a cutting tool.
Methods for manufacturing a matrix with at least one surface section displaying a negative microstructure, in which the matrix is suitable for inclusion in a mould cavity, as a mould cavity insert in a unit producing plastic components, in order to assign said plastic components a corresponding surface section with corresponding positive microstructure, wherein an original with a surface section displaying a positive microstructure is used in order to apply on this original layer upon layer of material and/or mixtures of material producing a matrix, and thereafter removing the matrix from said original or removing the material in the original, are also known.
In a method as described above it is also known to coat the negative microstructure, in a subsequent treating process, with a material layer that per se has good durability qualities against stresses in the plastic moulding unit when used as a mould-cavity insert.
It is also known that each application of such additional, reinforcing materials on a matrix results in somewhat deteriorated exactitude in the negative microstructure of the matrix, and thus somewhat deteriorated quality of the positive microstructure to be transferred to the plastic component.
It is also known that the wear caused by a plastic compound on the mould-cavity insert is considerable and that the surface displaying the microstructure must be coated with a material that will stand up to wear, particularly if the plastic compound contains an abrasive filler such as quartz.
Such filler materials may also be selected from materials that will give a low thermal expansion coefficient, such as 0 or close to zero, or may offer reinforcing properties from the mechanical aspect.
The following publications also pertain to prior art in this field:
D1) Patent Abstracts of Japan, abstract of JP 2 225 668, publ. 1990-09-07 and JP-2 225 688-A and Derwent""s abstract, No. 1990-316 827, week 9042.
A method is shown and described here for producing a core with an exact relief-related pattern on its surface, a non-electrical plated coating of a first layer on the surface of the core, and dipping the platedcore in an alectro-bath prior to oxidation of the non-electrical plating coating is undertaken. A strong union is ensured between the model and the non-electrical coating.
It is advocated here that an epoxy plastic is supplied via an inlet (9b), as a reinforcing agent (9a), through which a counterdie (9) is formed with a reversed pattern (8). Thereafter a non-electrical plating coating is applied on the counterdie or core (9) to produce a plated coating (10).
This coating (10) increases in hardness since a mixture of a component of a reducing agent in the plating bath and a plated metal is utilised, thus producing a reversed pattern (1).
Before the surface of the plated coating is oxidised or after the surface has been roughened, an electro-formed layer 12 is applied on the above surface.
By subsequently peeling off the above-mentioned laminating coatings of the counterdie (9), an electro-formed mould body (1) is obtained, consisting of a plated layer (10) and an electroformed layer (12), which is improved from the adhesive aspect, and has an inverted pattern (11).
D2) Patent Abstracts of Japan, abstract of JP 3 342 787, publ. 1991-10-30 and JP-3 243 787-A and Derwent""s abstract, No. 1991-364 686, week 9150.
A mould (4) made of metal is shown here, provided with a mould-producing recess in the form of a deep hole (51) with a ridge (52).
In this case a master with protrusions (11 and 12) corresponding to the hole (51) and the ridge (52) consists of aluminium.
A nickel-plated layer (2), including fine hard ceramic particles of SiC, TiC, TiN, etc, is formed on the surface of the master pattern (1).
A shell (3) consisting of nickel is also formed.
The pattern is dissolved in NaOH and removed, and the remaining part of the shell (3) is shaped to a specific size and inserted in the concave part of the mould (4).
A plated layer is thus formed with a hard and uniform surface, in which the ceramic particle-shaped material is uniformly distributed and facilitates release of the moulded product from the mould.
D3) EP-400 672-A2.
A technique is shown and described here for producing a mould enabling replication of a large number of plastic components.
The mould displays a hologram or other microstructure to be transferred to the outside of a moulded article or component.
The mould is produced by electro-depositing a metal on the model of the article to be moulded.
Prior to this deposition the hologram or other microstructure shall be formed on the surface areas of the model by means of known technology.
D4) Patent Abstracts of Japan, abstract of JP 4 089 212, publ. 1992-03-23 and JP-4 089 21 2-A and Derwent""s abstract, No. 1992-147 406, week 9218.
An arrangement is shown here in which plastic is introduced between a mould (1) and a glass lens (5), the plastic hardening so that a plastic layer (4) is formed on the lens (5), with an intermediately oriented carbon film (2).
D5) Patent Abstracts of Japan, abstract of JP 5 169 459, publ. 1993-07-09 and JP-5 169 459-A and Derwent""s abstract, No. 1993-252 170, week 9332.
This shows a base material for a mould and part of this is coated with a hard carbon film or diamond-like carbon film (DLC-film).
D6) EP-856 592-A1
This shows and describes a substrate (1) that is covered, at least partially, with a layer (1) consisting of a number of layer build-ups (2), each such build-up comprising:
a first diamond-like layer (3) consisting of nano-composites, nearest the substrate and displaying co-operating networks of a C:H and a Si:O,
a second layer (4) consisting of diamond-like composites, over said first layer (3),
an intermediate layer (5) between said first and second layers, consisting of a mixture of said first and second layer, and
when the number of layer structures above exceeds one (1), an additional intermediately oriented layer (7) is provided.
D7) GB-2 284 175A
This shows and describes a mould with exceptionally good release capability, particularly in the production of golf-ball cores.
Also proposed is for the mould to be covered by a tungsten carbide layer within the range of 2 to 20 xcexcm.
D8) U.S. Pat. No. 4,546,951-A
Here a mould is shown and described for encapsulating parts in a plastic material.
A layer of hard material, such as a nitrite layer, is applied by means of vapour deposition in vacuum at a high temperature on to at least specifically selected surface areas.
Technical Problems
Considering that the technical deliberations a person skilled in the art must perform in order to be able to offer a solution to one or more of the technical problems posed constitute initially an insight into the measures and/or the sequence of measures to be taken, and also a selection of the means required, the following technical problems should be relevant in developing the object of the present invention.
Considering the previous state of the art as described above, it would appear to be a technical problem to create such conditions that a matrix, produced against an original, shall have a durable first material layer for building up the matrix, where this material layer shall also display such properties that, with simple additional treatments, the matrix can be placed directly in a mould half, as a mould-cavity insert, in a unit for producing plastic components.
A technical problem exists in being able to select at least said first material layer for forming the matrix, with favourable properties appropriate for the intended future application, as regards such criteria as durability, predisposition of the plastic material to release from the microstructured surface or surfaces of the matrix, and other equivalent conditions.
A technical problem is also entailed in being able to perceive the significance of and advantages associated with having a first thin layer of material applied against the original to form the matrix, be selected with exceptionally good durability properties in the manufacture of plastic components, exceptionally good properties as regards the ability and predisposition of the plastic component to release from the matrix after moulding, curing or polymerisation of the plastic material used (low friction), and exceptionally good properties as regards retaining a sharp pattern on the microstructured surface section.
A technical problem is also entailed in being able to perceive the significance of and advantages associated with selecting a thin diamond-related material layer as said first material layer that, besides hard and durable properties, also displays low friction and exceptionally good release properties from the moulded plastic component.
It is furthermore a technical problem to be able to perceive the significance of and advantages associated with utilising application methods based on a crystalline diamond coating, such as CVD (Chemical Vapour Deposition) technology (750-800 degrees C.) or PVD (Physical Vapour Deposition) technology.
It is furthermore a technical problem to be able to perceive the significance of and advantages associated with utilising application methods based on an application of a hard and durable material layer with lower temperature requirements or DLC (Diamond-Like Carbon) layer (ca. 200 degrees C.), such as nitrides, carbides and the like.
It is thus a technical problem to select a layer produced using CVD technology or a DLC layer or some other layer material that has proved relevant for a specific application.
A technical problem is also entailed in being able to perceive the significance of selecting said first material layer with a predetermined thickness, the selected thickness being dependent on the material chosen for the first material layer, the shape and dimensions of the microstructure, and the choice of plastic material and of filler.
It would also appear to be a technical problem to be able to choose a material and/or a material mixture in a second and/or a third layer (an intermediate layer) in combination with a chosen thickness for the material in these layers.
A technical problem is also entailed in being able to perceive the significance of and advantages associated with selecting a utilised original in the form of a silicon disc or the like, with a positive microstructure thereon, and in having said silicon disc removable by means of a basic etching after the matrix has been built up.
A technical problem is also entailed in being able to perceive the significance of selecting KOH, NaOH or similar liquids for said basic etching.
A technical problem is also entailed in being able to perceive the significance of and advantages associated with selecting a mixture of DLC and Ni as a second material layer.
A technical problem is also entailed in being able to perceive the significance of selecting said second material layer with a thickness appropriate to the application.
A technical problem is also entailed in being able to perceive the significance of utilising a third material layer and, in that case, selecting only nickel or at least primarily nickel to form the third material layer.
A technical problem is furthermore entailed in being able to perceive the significance of selecting said third material layer with a thickness appropriate to the application.
A technical problem is also entailed in being able to perceive the significance of selecting a plating of nickel material as a fourth material layer and in selecting a thickness of said layer appropriate to the application.
A technical problem is also entailed in being able to perceive the significance of applying said first material layer, consisting of a DLC layer, by means of a sputtering process.
A technical problem is also entailed in being able to perceive the significance of applying said second material layer, consisting of a mixture of DLC and Ni, by means of a sputtering process.
Solution
In order to solve one or more of the above technical problems, the point of departure for the present invention is a method for the manufacture of a matrix, and a matrix thus produced, with at least one surface section displaying a microstructure, which matrix is suitable for inclusion in a mould cavity or in a cavity, while forming a mould insert, in a unit producing plastic components, in order to assign said plastic components an opposing microstructure in a corresponding surface section, an original being used in order to apply on this original layer upon layer of a material and/or mixtures of materials producing a matrix, and thereafter remove the matrix from said original or, preferably, remove the material in the original in order to expose the matrix and the surface pertaining to the microstructure.
In such a known method, it is proposed according to the invention that a first layer of material is applied against the original so that, together with a number of additional layers of material, said matrix is formed, that the first layer of material is selected having exceptionally good durability properties in the manufacture of plastic components, exceptionally good properties as regards the ability of the plastic component to release from the matrix after moulding, curing or polymerisation of the plastic material used, and exceptionally good properties as regards retaining the pattern on the microstructured surface section.
Preferred embodiments falling within the scope of the inventive concept include the selection of a hard, durable, thin layer of material with low friction and good release properties from the plastic material, for said first layer of material.
Said first material layer may be a crystalline diamond layer, such as a DLC layer or a layer that can be applied using CVD technology and/or PVD technology (Physical Vapour Deposition).
For certain applications the first material layer could also consist of nitrides, carbides and the like.
The first material layer should be applied to a thickness of 0.1-100 xcexcm.
A second material layer, with good adhesive capability to the first material layer, is applied on the first, where the second material layer may consist of DLC, titanium and/or chromium.
Said second material layer should be applied to a thickness of 0.05-2.0 xcexcm.
A third material layer, with good adhesive capability to the second material layer, is applied on the second layer and said third material layer may consist of a nickel layer.
Said third material layer should be applied to a thickness of 0.05-2.0 xcexcm.
Said second material layer and said third material layer may also be combined to an intermediately oriented layer having a chosen high DLC proportion or a high titanium and /or chromium concentration at a boundary surface to said first material layer and a high nickel concentration at a boundary surface to a bulk material in the form of a fourth layer, serving as mechanical support.
Said first material layer may preferably be chosen having a thickness of 1-15xcexcm.
The invention also advocates selecting a treated silicon disc or the like with a chosen microstructure, as an original, and that said silicon disc can be removed by means of a basic etching.
The use of KOH, NaOH or equivalent basic liquids are proposed for this basic etching.
According to the invention a mixture of DLC and nickel may be selected as a second material layer.
Said second material layer may preferably be chosen having a thickness of 0.05-1.0 xcexcm.
The invention also proposes applying a third layer of material and selecting nickel for this third material layer.
Said third material layer may then be chosen having a thickness of 0.05-1.0 xcexcm.
As a fourth layer of material the invention proposes that this be applied in a plating process and shall consist of pure nickel.
Said fourth material layer may be chosen with a thickness appropriate for the application.
The invention particularly advocates application of a DLC layer or similar by means of a sputtering process in combination with the application of DLC and nickel, serving as a second material layer, by means of a sputtering process.
The third material layer may also be applied by means of a sputtering process.
The second and the third material layers may also be applied, integrated, by means of a sputtering process.
The ratio between the proportion of DLC and the proportion of nickel shall advantageously be chosen varying through the layer and with 50% of each in the mid-region of the layer.
Advantages
The advantages that may primarily be deemed significant for a method in accordance with the present invention, and a matrix manufactured in accordance with the method, are that conditions have been created to be able, in a simple manner, to create a matrix suitable for a mould-cavity insert, with a hard, durable, thin and sharp microstructured surface facing towards the plastic material in a moulding tool.
The material in this thin layer, which may comprise a DLC layer of 0.1-100 xcexcm, is such and so chosen that the microstructured surface of the matrix will display good release properties with regard to a chosen plastic material and the pattern in the matrix can be retained intact over a long period of time.
A matrix in accordance with the invention is built up of a number of thin layers of material and a thick layer of bulk material, serving as mechanical support.
What is primarily deemed characteristic of a method for manufacturing a matrix in accordance with the present invention is defined in the characterizing part of the appended claim 1, and for a matrix preferably manufactured by means of the method, is defined in the characterizing part of the appended claim 27.